Systems and methods for assesing vulnerability of non-line of sight targerts

ABSTRACT

A computer-implemented system and method of determining the vulnerability of an asset includes determining an elevation surface surrounding an asset. A target point and aim point are selected on the asset and ballistic trajectories are determined for a particular projectile. A plurality of trajectory height surfaces that are rotationally symmetric about the asset and having a cross-section corresponding to the projectile trajectory for the selected range. A corrected elevation surface is generated for each range based on the trajectory height surface for the particular range. An observer view surface is generated from the plurality of corrected elevation surfaces, and is combined with the target visibility surface to generate the target vulnerability surface.

FIELD OF INVENTION

This disclosure concerns determining vulnerabilities of assets to riflefire and other ballistics from geographic positions surrounding theassets.

BACKGROUND

Security of industrial and utility assets and infrastructure can be animportant consideration in operation of such assets and infrastructure.There has been an effort to place fencing and earthen berms around manyfacilities with the intent of protecting the assets and personnel insidethe facilities. However, the protection is typically only designed toshield sight lines within a short distance of the facility. Suchobstructions are not optimal as long range rifles can be used to hittargets outside of the shooters sight line. With recently developedarmor piercing ammunition, many of the otherwise protected assets areeffectively within range. Thus a systems and methods for determiningvulnerabilities from locations that do not have a line of sight to thetarget are desirable.

SUMMARY OF THE INVENTION

The present disclosure concerns determining effective rifle sight linesfor a geographic area surrounding assets and infrastructure. Accordingto one aspect of the present disclosure, modifications to the elevationof surrounding terrain are made to account for bullet trajectory anddrop. Thus, locations are identified in the surrounding area that do nothave direct lines of sight, but can nevertheless serve as shootinglocation for a rifleman intent on hitting the asset.

A computer-implemented system and method of determining thevulnerability of an asset includes determining an elevation surfacesurrounding an asset. A target point and aim point are selected on theasset and ballistic trajectories are determined for a particularprojectile over a plurality of isotropic bands at various ranges. Aplurality of trajectory height surfaces are generated for the variousranges that are rotationally symmetric about the asset and having across-section corresponding to the projectile trajectory for theparticular range. A corrected elevation surface is generated for eachrange based on the trajectory height surface for the particular range.An observer view surface is generated from the plurality of correctedelevation surfaces, and is combined with the target visibility surfaceto generate the target vulnerability surface.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, structures and methods are illustratedthat, together with the detailed description provided below, describeaspects of a system determining the vulnerability of assets to non-lineof sight fire, and related methods. It will be noted that a singlecomponent may be implemented as multiple components or that multiplecomponents may be implemented as a single component. The figures are notdrawn to scale and the proportions of certain parts have beenexaggerated for convenience of illustration. Further, in theaccompanying drawings and description that follow, like parts areindicated throughout the drawings and written description with the samereference numerals, respectively.

FIG. 1 (“FIG. 1”) illustrates a diagram of system 100.

FIG. 2 illustrates a subject asset 102.

FIGS. 3A-3E illustrate sight lines and trajectories for variousobstructions 301-305.

FIG. 4 illustrates a filtered raster 400.

FIG. 5 illustrates an aim visibility surface 500 overlaid on elevationsurface 404.

FIG. 6 illustrates a target visibility surface 600 overlaid on elevationsurface 404.

FIG. 7 illustrates a comparison of aim visibility surface 500 and targetvisibility surface 600.

FIG. 8 illustrates a trajectory height surfaces 800 overlaid onelevation surface 404.

FIG. 9 illustrates a corrected elevation surface 900.

FIG. 10 illustrates observer view surface 1002.

FIG. 11 illustrates target vulnerability surface 1100 overlaid onelevation surface 404.

FIG. 12 illustrates target visibility surface 600 overlaid on targetvulnerability surface 1100.

FIG. 13 illustrates a method 1300 for determining asset 102vulnerability.

DETAILED DESCRIPTION

With reference to FIG. 1, a system 100 for evaluating the vulnerabilityof assets 102 includes a computing device 104, which can be a generalpurpose computer or specialized computer, and can be portable, desktopor handheld. The computer includes a processor 106 and non-transientcomputer readable medium (CRM) 108, which can include without limitationhard drives, random access memory, flash-based drives, caches,registers, optical drives, or other form of non-transientcomputer-readable media.

The evaluation of vulnerability of an asset 102 includes providinggeographic data 110 including but not limited to elevation data of thegeographic region of interest surround the asset 102. Asset data 112includes the structure, dimensions, target and aim points, and otherinformation concerning asset 102. Ballistic data 114 includes dataconcerning the specifications of the particular projectile. This caninclude a trajectory height function dependent on the distance traversedby the projectile. The geographic data 110, asset data 112, andballistic data 114 can be stored on the CRM 108, such as in storagelocations 116 a, 116 b, 116 c, etc. Processor 106 can executeinstructions 118 written on CRM 108, including those instructionsdescribed herein, to determine target vulnerability 120 and protectivebarrier placement 122 that would mitigate against potentialvulnerabilities by blocking one or both of the shooter's ability to seethe aim point or hit the target point with a projectile such as a riflebullet.

With reference to FIG. 2, asset 102 has a warning light 130 at itshighest point, which is at a height of 24 meters above the groundsurface 132. In this case, the aim point 200 can be selected as thehighest point of the particular asset 102, which would be the minimumamount of the asset 102 that the potential shooter would be required tosee in order to determine the position of the remainder of the asset102. When a potential shooter is able to see only the aim point 200, theremainder of the asset 102 can be obstructed by the terrain between thepotential shooter and the asset 102. The selected target point 202 is 12meters above the ground and is at the equatorial latitude of the tank.The asset 102 has a diameter of 20 meters. The illustrated target point202 and aim point 200 are non-limiting and can be selected at anydesired points on the asset 102. The aim point 200 is preferably abovethe target point 202, and as described further herein thresholds can bechosen under which further analysis for the selected target point 202and aim points 200 is not necessary. Target points 402 can be chosenbased upon factors including but not limited to known structuralvulnerabilities of the asset, intelligence gathering, the likelihood ofa non-failure mode strike by a projectile at the selected target point,and others. Aim points 200 can likewise be chosen at any reference pointon the asset 102, however, the amount of available terrain from which toview aim points 200 decreases as the selected aim point 200 movesfurther below the highest possible aim point 200. Conversely, selectingthe highest possible aim point 200 provides the maximum amount ofpossible terrain from which to view the selected aim point 200.

FIGS. 3A-3E illustrate sight lines and trajectories from a shooterfiring and viewing from 1 meter above the ground to an asset 102 overdifferent geographic obstructions 301-305 having different heights andshapes. In FIG. 3A the target point 202 is visible along direct sightline 310, and so it is accessible to a shooter at that location. In FIG.3B, the target point 202 is not visible along direct sight line 310, butthe aim point 200 is visible along the indirect sight line 312. In thiscase, a shooter can still hit the target point 202 as the projectiletrajectory 314 is not impeded by obstruction 302. The locations fromwhich a shooter cannot view the target point 202 but can see the aimpoint 200 and can reach the target point 202 over interveningobstructions with the projectile trajectory 314 can be determinedaccording to the present teachings. In FIGS. 3C through 3E, at least oneof the trajectory 314 or the indirect sight line 312 are blocked byintervening obstructions 303, 304, 305.

With reference to FIG. 4, a filtered raster 400 corresponding to a threedimensional elevation surface is created from detailed raster data. Theinitial detailed raster data is obtained from multiple Light Detectionand Ranging (LIDAR) files, which can be simple ASCII files wherein eachline includes a coordinate (x, y, z) wherein x and y are latitude andlongitude and z is the altitude for the particular (x, y) coordinate.Other forms of files, including without limitation CAD files or GISfiles, can include data that can be implemented according to the presentteachings. The multiple LIDAR files each cover separate areas within theregion 402 surrounding the asset 102, which is disposed in the center ofthe surrounding region 402. The depicted surrounding region 402 iscircular with a radius of 5000 meters. Any data contained within theLIDAR files outside of the surrounding region 402 can be masked off andignored.

The initial raster data is filtered by removing anomalies and noise dueto, for example, conversion of raster data and incorrect surfaceelevations from power lines and other localized objects disposed withinthe surrounding region 402. A resulting filtered elevation surface 404is generated from the filtered raster data, and can be used to evaluateasset 102 vulnerabilities as described herein.

With reference to FIG. 5, an aim visibility surface 500 is determinedover the elevation surface 404, representing the locations on thesurface 404 from which an potential shooter firing and viewing from aheight of 1 meter can see the aim point 200 of the asset 102, which inthe illustrated case corresponds to the surface elevation at the assetplus 24 meters. A location on the elevation surface 404 is part of theaim visibility surface 500 if a line from the aim point 200 of the asset102 to a point 1 meter above the potential shooter's particular locationon the elevation surface 404 is unobstructed. At such a location on theelevation surface 404, the potential shooter will have an unobstructedline of sight to the aim point 200.

With reference to FIG. 6, a target visibility surface 600 is determinedover the elevation surface 404, representing the locations on thesurface 404 from which a potential shooter, again viewing from a heightof 1 meter, can see the target point 202 of the asset 102, which in theillustrated case corresponds to the surface elevation at the asset plus12 meters. A location on the elevation surface 404 is part of the targetvisibility surface 600 if a line from the target point 202 of the asset102 to a point 1 meter above the ground at the particular location onthe elevation surface 404 is unobstructed. At such a location on theelevation surface 404, the potential shooter will have an unobstructedline of sight to the target point 202.

With reference to FIG. 7, a comparison of the aim visibility surface 500and the target visibility surface 600, which in the illustrated case isoverlaid on aim visibility surface 500, exposes the locations 501 thatare within the aim visibility surface 500 and not the target visibilitysurfaces 600. A shooter at any of those locations has a line of sight tothe aim point 200 but not the target point 202, rendering thoselocations 501 potential candidates for trajectory-assisted firing uponthe asset 102. In those locations 501, the shooter cannot see the targetpoint 202 but can potentially reach the target point 202 with thebenefit of the aim point 200 and a shot fired along the correcttrajectory, which trajectory has boundary conditions satisfying theselection of the target point 202 and the elevation of the shooter'srifle and viewpoint. The locations 501 combined can be required to havea threshold amount of surface area such that below the threshold, nofurther determination of possible vulnerabilities according aredesirable as the amount of risk is acceptably low. In such a cases thepotential locations for an obstructed shooter, i.e. one that has view ofthe aim point 200 but not the target point 202, are few enough that theydo not add sufficiently substantial risk in addition to the risk posedfrom the target visibility surface 600 alone. Such a threshold can bepredetermined at any desirable amount, including but not limited to 1percent, 5 percent, 10 percent or 25 percent of the total surface areaof the target visibility surface 600.

With reference to FIG. 8, several steps are performed in order to createa corrected elevation map for evaluating vulnerabilities. A set oftrajectory height surfaces 800 are created. These surfaces 800 can beisotropic, and can correspond to the path of the projectile from a pointon the outer edge of the ring to the target point 202 and swept onerevolution about the target point 202. One trajectory height surface 800is generated for each of several circular rings surrounding the asset102, the rings starting at 500 meters radius and extending to 1900meters, each ring 100 meters thick along the radial direction. FIG. 8shows the 1900 meter trajectory height surface 800 overlaid on elevationsurface 404.

With reference to FIG. 9, a set of corrected elevation surfaces 900 isgenerated based on the set of trajectory height surfaces 800. Onecorrected elevation surface 900 is generated for each trajectory heightsurface 800, from 500 to 1900 meters, by subtracting the height of thetrajectory height surface 800 from the corresponding base elevation ofelevation surface 404. A corrected region 902 can be seen in FIG. 9,which again corresponds to the 1900 meters ring, in which the elevationhas been corrected and appears darker than in elevation surface 404. Inthat region 902, the altitude of the terrain is lower than that found insurface 404. The trajectory of the projectile can be obtained bydetermining projectile data, such as ballistic information including butnot limited to the shape of the projectile, ballistic coefficient,projectile diameter, weight composition, and muzzle velocity. Such datacan be obtained from a variety of sources, including but not limited tomodeling software. In addition, results from models can further becurve-fit in order to obtain a finite order polynomial with which tocalculate the surfaces 800. In the illustrated case, projectiletrajectory was fit to a fifth order polynomial. It should be noted thatthe present teachings can be applied to a variety of rifle cartridges orto small arms such as rocket propelled grenades, infantry mortars, lightcannon and indirect machine gun attacks. Further, corrected altitude canbe performed on a location by location basis, rather than in wide rings.In such an approach, trajectories are calculated incrementally for eachposition in the region, and the corrected altitude surface is generatedfor each individual position.

With reference to FIG. 10, from each of the corrected elevations, anobserver view is generated. The range for each observer view is one offifteen 100 meter thick visibility rings surrounding the asset 102, withthe inner radius chosen as the coordinate for which the correspondingelevation is selected for the ring. Other points can be selected for theelevation calculation. The outer ring corresponds to the potentialshooter's view for 1900 to 2000 meters and the inner ring corresponds tothe view for 500 to 600 meters from the asset 102. The highlightedportions within each ring correspond to the locations where an observerat the target point 202 can view the potential shooter viewing andfiring from 1 meter elevation over the corrected elevation. The rings1000 can be joined, for example by a logical OR function wherein acoordinate is part of an observer view surface 1002 if it is visiblewithin its respective ring 1000.

With reference to FIG. 11, the observer view surface 1002 can becombined with the target visibility surface 600 to create targetvulnerability surface 1100. Locations on the target vulnerabilitysurface 1100 are locations where either the target point 202 is visibleor the aim point 200 is visible and the target point 202 is reachablewith a projectile shot along the correct trajectory. With reference toFIG. 12, the target visibility surface 600 is overlaid on targetvulnerability surface 1100 in order to illustrate the additional area1200 from which a potential shooter can reach the target point 202. Thisadditional area corresponds to surface that is part of the targetvulnerability surface 1100 but not the target visibility surface 600. Inthe current example, the increase in surface area over the targetvisibility surface 600 is 23 percent. It should be noted that thevarious surfaces referred to herein, such as the target vulnerabilitysurface 1100 or target visibility surface 600, need not be contiguous,and can have one or more separate domains.

With reference to FIG. 13, a method 1300 for determining thevulnerability of an asset includes receiving high resolution elevationdata for the asset and the surrounding area of interest in step 1302. Instep 1304, ballistic trajectory data is received, which data can bedetermined by simulations of projectile shots and subsequent curvefitting of the resulting data to a curve that can be used to describethe projectile's trajectory as a function of its position relative tothe asset 102. In step 1306, the position of the aim point 200 andtarget point 202 of the asset 102 are selected. In step 1308, an aimvisibility surface 500 is created from the elevation map 404. In step1310, a target visibility surface 600 is created from the elevation map404. In step 1312, the target visibility surface 600 is compared to theaim visibility surface 500, for example to determine whether sufficientaddition surface area is present in the aim visibility surface 500 overthe target visibility surface 600 to justify continued analysis. In oneaspect of the present teachings, step 1312 can be omitted and the othersteps described herein can be performed without limitation.

In step 1314, a set of trajectory height surfaces 800 are generated, oneeach for a series of ranges from an inner range to an outer range. Thetrajectories used to form the trajectory surfaces 800 can be calculatedfrom a curve fit polynomial as described herein, with boundaryconditions that one end be at the target point 202 and the other at apredetermined elevation at a location disposed at the particular range.The trajectories are swept around the asset 102 so to form arotationally symmetric surface 800 such that a cross-sectional view ofthe surface 800 along the radial direction exposes the trajectory usedto form the surface 800. In step 1316, a set of corrected elevationsurfaces 900 are determined, one for each of the selected ranges, usingthe trajectory surface 800 for the particular range. In step 1318, a setof observer point visibility surfaces are generated for each of theplurality of ranges. In step 1320, all of the visibility surfaces of thevarious ranges are combined to form the observer view surface 1002. Instep 1322, the target visibility surface 600 and observer view surface1002 are combined to form a target vulnerability surface 1100. In step1324, the target visibility surface 600 is subtracted from the targetvulnerability surface 1100 in order to illustrate the additional area1200 from which a potential shooter can reach the target point 202.

The vulnerability analysis disclosed herein can be performed based onmultiple targets in an area. Such an analysis could involve trajectoryheight surfaces radiating each of the target assets instead of a singletarget point. The methods disclosed herein can also be used to determineeffective locations for visual and ballistic barriers.

The present teachings can be used to determine maximum distances fromthe asset 102 that could damage the asset 102 based on penetrationangle, terminal energy and target shell material. Further, the presentteachings can be implemented to determine the effective impact areabased on maximum penetration angle of the projectile. The calculationsperformed herein can be extended to other target shapes, such asvertical, horizontal, and flat cylinders.

In the present disclosure, reference numerals followed by alphabeticindices refer to one of the illustrated elements, while use of thereference numeral without the alphabetic indices refer to one or more ofthe illustrated elements. For the purposes of this disclosure and unlessotherwise specified, “a” or “an” means “one or more.” To the extent thatthe term “includes” or “including” is used in the specification or theclaims, it is intended to be inclusive in a manner similar to the term“comprising” as that term is interpreted when employed as a transitionalword in a claim. Furthermore, to the extent that the term “or” isemployed (e.g., A or B) it is intended to mean “A or B or both.” Whenthe applicants intend to indicate “only A or B but not both” then theterm “only A or B but not both” will be employed. As used herein,“about” will be understood by persons of ordinary skill in the art andwill vary to some extent depending upon the context in which it is used.If there are uses of the term which are not clear to persons of ordinaryskill in the art, given the context in which it is used, “about” willmean up to plus or minus 10% of the particular term. From about A to Bis intended to mean from about A to about B, where A and B are thespecified values.

The description of various embodiments and the details of thoseembodiments is illustrative and is not intended to restrict or in anyway limit the scope of the claimed invention to those embodiments anddetails. Additional advantages and modifications will be apparent tothose skilled in the art. Therefore, the invention, in its broaderaspects, is not limited to the specific details and illustrativeexamples shown and described. Accordingly, departures may be made fromsuch details without departing from the spirit or scope of theapplicant's claimed invention.

1. A computer-implemented method of determining the vulnerability of anasset, comprising: generating an elevation surface for a regionsurrounding an asset having elevations; determining a target point andaim point of the asset; determining ballistic trajectories for aplurality of distances from the asset to the target point; generating aplurality of trajectory height surfaces rotationally symmetric about theasset and having a cross-section with a first end at the target pointand second end at the radially outer edge of the surface at a distancecorresponding to one of the plurality of distances from the asset;generating a plurality corrected elevation surfaces by subtracting eachof the trajectory height surfaces from a respective elevation surfaces;and, generating an observer view surface from the plurality of correctedelevation surfaces.
 2. The method of claim 1, further comprising:determining a target visibility surface based on the elevation surfaceand the target point.
 3. The method of claim 2, further comprising:determining a target vulnerability surface based on the targetvisibility surface and observer view surface.
 4. The method of claim 2,further comprising: determining an aim visibility surface based on theelevation surface and aim point; and, comparing a surface area of theaim visibility surface and a surface area of the target visibilitysurface.
 5. The method of claim 1, wherein the step of determining atarget point and aim point of the asset includes selecting the highestvisible point on the asset as the aim point.
 6. The method of claim 1,wherein the step of determining a target point and aim point of theasset includes selecting the aim point at a location above the targetpoint.
 7. The method of claim 1, wherein the generating an observer viewsurface step includes selecting one of the plurality corrected elevationsurfaces corresponding to one of the plurality of distances from theasset and determining whether locations at the one of the plurality ofdistances from the asset have an unobstructed line of sight to thetarget point over the selected one of the corrected elevation surfaces.8. The method of claim 7, wherein the generating an observer viewsurface step includes, for each corrected elevation surface, determiningwhether locations at one of the plurality of distances from the assethave an unobstructed line of sight to the target point over the selectedone of the corrected elevation surfaces.
 9. The method of claim 1,wherein the determining ballistic trajectories step includes performinga curve fit calculation based on ballistic trajectory data to obtain atrajectory function, and calculating the trajectories based on thefunctions.
 10. An article of manufacture comprising: a non-transientcomputer-readable medium including instructions thereon that uponexecution by a processor: determine an elevation surface for a regionsurrounding an asset; determine a target point and aim point of theasset; determine ballistic trajectories for a plurality of distancesfrom the asset to a target point on the asset; generate a trajectoryheight surfaces for each of a plurality of ranges having a radialdistance from the asset, the trajectory height surfaces beingrotationally symmetric about the asset and having a cross-section with afirst end at the target point and second end at a ballistic firing pointat an outer edge of the trajectory height surface; generate a correctedelevation surfaces for each of the ranges by subtracting each of thetrajectory height surfaces for the particular range from a respectiveelevation surfaces; and, generate an observer view surface from theplurality of corrected elevation surfaces.